Analysis of Bryde’s whale calls observed close to the Costa Rica Rift, Eastern Tropical Pacific Ocean

• Main Authors: Tary, J. B., Peirce, C., Hobbs, R. W., Poveda, S., Bonilla Walker, F., De La Hoz, C., Li, K. L., Bird, A., Vargas, C. A.
• Format: Conference Object
• Language: English
• Subjects: baleen whales
• Online Access: https://dair.dias.ie/id/eprint/1399/; https://dair.dias.ie/id/eprint/1399/1/IGRM_poster_whales.pdf

Baleen whales use sounds of different characteristics when they interact with their environment. In this study, we use the hydrophone time series of 25 ocean bottom seismometers and a vertical array of 12 hydrophones, deployed close to the Costa Rica Rift in the Eastern Tropical Pacific Ocean between January and February 2015. The instruments recorded multiple whale calls that can be classified into two groups: the more common ones correspond to repetitive signals of 4-5 seconds, with two main frequencies at 20 and 36 Hz; the less common calls are shorter (0.5-1 seconds), lower amplitude signals with higher frequencies between 80 and 160 Hz. These properties match those of Bryde's whale calls, a whale specie occasionally observed in this region. The calls were then systematically detected and located using different methods used in seismology such as subspace detection, deep learning, non-linear grid search location, double-difference relocation, and probabilistic back-projection. The detailed locations show at least seven whales present at different times during the deployment, often moving from the Southwest to the Northeast over the network.